The Beaver has been hunted not only for its fur, but also, and from time immemorial, for the sake of a peculiar secretion produced by it, which, under the name of _Castoreum_, has been for many centuries a highly-esteemed medicament. This substance is secreted in a pair of glandular pouches, situated in the inguinal region of the male Beaver; and it would seem that it was almost entirely in order to procure these that the ancients hunted this animal. Even in connection with this they had wonderful tales to tell of its sagacity: as how that, when it was pursued and found itself unable to escape, it would throw itself upon its back, as if to invite the hunter to take what he wanted and spare its life. Nay, some ancient writers seem to have believed that the Beaver would go the length of biting off its own castoreum glands, and leaving them for the hunter to pick up! Castoreum contains some volatile oil and resin, and a peculiar crystallisable substance called castorine; it is used in medicine as a stimulant, and seems to act especially on the nervous system, but is not much employed nowadays. Its odour, which appears to spread over a considerable space, is described as being very attractive to other Beavers. Audubon states that it is used for this reason as a lure by the American trappers. CHAPTER II. THE DORMOUSE, LOPHIOMYS, RAT, AND MOUSE FAMILIES. THE MOUSE-LIKE RODENTS--MYOXIDÆ--Characteristics--THE DORMOUSE--Description--Habits--Activity--Food--Winter Condition--THE LOIR--THE GARDEN DORMOUSE--LOPHIOMYIDÆ--How the Family came to be Founded--THE LOPHIOMYS--Milne-Edwards’ Opinion--Skull--General Form--Habits--MURIDÆ--Number of Species--Characteristics--Variety of Forms--Distribution--The Murine Sub-Family--THE BROWN RAT--History--Fecundity and Ferocity--Diet--At the Horse Slaughter-houses of Montfaucon--Shipwrecked on Islands--Story of their Killing a Man in a Coal-pit--In the Sewers of Paris and London--THE BLACK RAT--THE EGYPTIAN RAT--THE COMMON MOUSE--Habits--Destructiveness--Colours--THE LONG-TAILED FIELD MOUSE--Description--Food--THE HARVEST MOUSE--Description--Habits--In Winter--Agility--Their Nest--THE BANDICOOT RAT--THE TREE RAT--THE STRIPED MOUSE--Allied Genera--THE WHITE-FOOTED HAPALOTE--The American Murines--THE WHITE-FOOTED, OR DEER MOUSE--THE GOLDEN, OR RED MOUSE--THE RICE-FIELD MOUSE--THE AMERICAN HARVEST MOUSE--THE FLORIDA RAT--Description--Their Nest--Food--Mother and Young--THE BUSHY-TAILED WOOD RAT--THE COTTON RAT--THE RABBIT-LIKE REITHRODON--THE HAMSTERS--Characteristics--Appearance--Distribution-- Burrows--Disposition--Food--Habits--THE TREE MICE--THE BLACK-STREAKED TREE MICE--THE GERBILLES--Characteristics--Habits--Other Genera--THE WATER MICE--Characteristics--Species--THE SMINTHUS--THE VOLES--Characteristics--THE WATER VOLE--Appearance--Distribution--Food--THE FIELD VOLE--THE BANK VOLE--THE SOUTHERN FIELD VOLE--THE SNOW MOUSE--THE ROOT